194 research outputs found
Continuous slice functional calculus in quaternionic Hilbert spaces
The aim of this work is to define a continuous functional calculus in
quaternionic Hilbert spaces, starting from basic issues regarding the notion of
spherical spectrum of a normal operator. As properties of the spherical
spectrum suggest, the class of continuous functions to consider in this setting
is the one of slice quaternionic functions. Slice functions generalize the
concept of slice regular function, which comprises power series with
quaternionic coefficients on one side and that can be seen as an effective
generalization to quaternions of holomorphic functions of one complex variable.
The notion of slice function allows to introduce suitable classes of real,
complex and quaternionic --algebras and to define, on each of these
--algebras, a functional calculus for quaternionic normal operators. In
particular, we establish several versions of the spectral map theorem. Some of
the results are proved also for unbounded operators. However, the mentioned
continuous functional calculi are defined only for bounded normal operators.
Some comments on the physical significance of our work are included.Comment: 71 pages, some references added. Accepted for publication in Reviews
in Mathematical Physic
Desempenho agronômico de linhagens de feijoeiro-comum de grãos especiais em sorriso - MT.
O presente trabalho teve por objetivo avaliar o desempenho agronômico de linhagens de feijoeiro com grãos especiais no estado de Mato Grosso.CONAF
Phytochrome-Based Extracellular Matrix with Reversibly Tunable mechanical Properties
Interrogation and control of cellular fate and function using optogenetics is providing revolutionary insights into biology. Optogenetic control of cells is achieved by coupling genetically encoded photoreceptors to cellular effectors and enables unprecedented spatiotemporal control of signaling processes. Here, a fast and reversibly switchable photoreceptor is used to tune the mechanical properties of polymer materials in a fully reversible, wavelength‐specific, and dose‐ and space‐controlled manner. By integrating engineered cyanobacterial phytochrome 1 into a poly(ethylene glycol) matrix, hydrogel materials responsive to light in the cell‐compatible red/far‐red spectrum are synthesized. These materials are applied to study in human mesenchymal stem cells how different mechanosignaling pathways respond to changing mechanical environments and to control the migration of primary immune cells in 3D. This optogenetics‐inspired matrix allows fundamental questions of how cells react to dynamic mechanical environments to be addressed. Further, remote control of such matrices can create new opportunities for tissue engineering or provide a basis for optically stimulated drug depots
Lower and upper probabilities in the distributive lattice of subsystems
yesThe set of subsystems ∑ (m) of a finite quantum system ∑(n) (with variables in Ζ(n)) together with logical connectives, is a distributive lattice. With regard to this lattice, the ℓ(m | ρn) = Tr ((m) ρn ) (where (m) is the projector to ∑(m)) obeys a supermodularity inequality, and it is interpreted as a lower probability in the sense of the Dempster–Shafer theory, and not as a Kolmogorov probability. It is shown that the basic concepts of the Dempster–Shafer theory (lower and upper probabilities and the Dempster multivaluedness) are pertinent to the quantum formalism of finite systems
Combinatoriality in the vocal systems of nonhuman animals
A key challenge in the field of human language evolution is the identification of the selective conditions that gave rise to language's generative nature. Comparative data on nonhuman animals provides a powerful tool to investigate similarities and differences among nonhuman and human communication systems and to reveal convergent evolutionary mechanisms. In this article, we provide an overview of the current evidence for combinatorial structures found in the vocal system of diverse species. We show that considerable structural diversity exits across and within species in the forms of combinatorial structures used. Based on this we suggest that a fine‐grained classification and differentiation of combinatoriality is a useful approach permitting systematic comparisons across animals. Specifically, this will help to identify factors that might promote the emergence of combinatoriality and, crucially, whether differences in combinatorial mechanisms might be driven by variations in social and ecological conditions or cognitive capacities
A new Late Agenian (MN2a, Early Miocene) fossil assemblage from Wallenried (Molasse Basin, Canton Fribourg, Switzerland)
Excavations of two fossiliferous layers in the Wallenried sand- and marl pit produced a very diversified vertebrate fauna. New material allows the reassessment of the taxonomic position of the ruminant taxa Andegameryx andegaviensis and endemic Friburgomeryx wallenriedensis. An emended diagnosis for the second species is provided and additional material of large and small mammals, as well as ectothermic vertebrates, is described. The recorded Lagomorpha show interesting morphological deviations from other Central European material, and probably represent a unique transitional assemblage with a co-occurrence of Titanomys, Lagopsis and Prolagus. Rodentia and Eulipotyphla belong to typical and well-known species of the Agenian of the Swiss Molasse Basin. Abundant small mammal teeth have allowed us to pinpoint the biostratigraphic age of Wallenried to late MN2a. The biostratigraphic age conforms to data derived from the charophyte assemblages and confirms the oldest occurrence of venomous snake fangs. The palaeoenvironmental context is quite complex. Sedimentary structures and fauna (fishes, frogs, salamanders, ostracods) are characteristic for a humid, lacustrine environment within a flood plain system
LensWatch: I. Resolved HST Observations and Constraints on the Strongly-Lensed Type Ia Supernova 2022qmx ("SN Zwicky")
Supernovae (SNe) that have been multiply-imaged by gravitational lensing are
rare and powerful probes for cosmology. Each detection is an opportunity to
develop the critical tools and methodologies needed as the sample of lensed SNe
increases by orders of magnitude with the upcoming Vera C. Rubin Observatory
and Nancy Grace Roman Space Telescope. The latest such discovery is of the
quadruply-imaged Type Ia SN 2022qmx (aka, "SN Zwicky"; Goobar et al. 2022) at z
= 0.3544. SN Zwicky was discovered by the Zwicky Transient Facility (ZTF) in
spatially unresolved data. Here we present follow-up Hubble Space Telescope
observations of SN Zwicky, the first from the multi-cycle "LensWatch" program
(www.lenswatch.org). We measure photometry for each of the four images of SN
Zwicky, which are resolved in three WFC3/UVIS filters (F475W, F625W, F814W) but
unresolved with WFC3/IR F160W, and produce an analysis of the lensing system
using a variety of independent lens modeling methods. We find consistency
between time delays estimated with the single epoch of HST photometry and the
lens model predictions constrained through the multiple image positions, with
both inferring time delays of <1 day. Our lens models converge to an Einstein
radius of (0.168+0.009-0.005)", the smallest yet seen in a lensed SN. The
"standard candle" nature of SN Zwicky provides magnification estimates
independent of the lens modeling that are brighter by ~1.5 mag and ~0.8 mag for
two of the four images, suggesting significant microlensing and/or additional
substructure beyond the flexibility of our image-position mass models
Human Neural Stem Cells Differentiate and Promote Locomotor Recovery in an Early Chronic Spinal coRd Injury NOD-scid Mouse Model
Traumatic spinal cord injury (SCI) results in partial or complete paralysis and is characterized by a loss of neurons and oligodendrocytes, axonal injury, and demyelination/dysmyelination of spared axons. Approximately 1,250,000 individuals have chronic SCI in the U.S.; therefore treatment in the chronic stages is highly clinically relevant. Human neural stem cells (hCNS-SCns) were prospectively isolated based on fluorescence-activated cell sorting for a CD133(+) and CD24(-/lo) population from fetal brain, grown as neurospheres, and lineage restricted to generate neurons, oligodendrocytes and astrocytes. hCNS-SCns have recently been transplanted sub-acutely following spinal cord injury and found to promote improved locomotor recovery. We tested the ability of hCNS-SCns transplanted 30 days post SCI to survive, differentiate, migrate, and promote improved locomotor recovery.hCNS-SCns were transplanted into immunodeficient NOD-scid mice 30 days post spinal cord contusion injury. hCNS-SCns transplanted mice demonstrated significantly improved locomotor recovery compared to vehicle controls using open field locomotor testing and CatWalk gait analysis. Transplanted hCNS-SCns exhibited long-term engraftment, migration, limited proliferation, and differentiation predominantly to oligodendrocytes and neurons. Astrocytic differentiation was rare and mice did not exhibit mechanical allodynia. Furthermore, differentiated hCNS-SCns integrated with the host as demonstrated by co-localization of human cytoplasm with discrete staining for the paranodal marker contactin-associated protein.The results suggest that hCNS-SCns are capable of surviving, differentiating, and promoting improved locomotor recovery when transplanted into an early chronic injury microenvironment. These data suggest that hCNS-SCns transplantation has efficacy in an early chronic SCI setting and thus expands the "window of opportunity" for intervention
Masonry compressive strength prediction using artificial neural networks
The masonry is not only included among the oldest building materials, but it is also the most widely used material due to its simple construction and low cost compared to the other modern building materials. Nevertheless, there is not yet a robust quantitative method, available in the literature, which can reliably predict its strength, based on the geometrical and mechanical characteristics of its components. This limitation is due to the highly nonlinear relation between the compressive strength of masonry and the geometrical and mechanical properties of the components of the masonry. In this paper, the application of artificial neural networks for predicting the compressive strength of masonry has been investigated. Specifically, back-propagation neural network models have been used for predicting the compressive strength of masonry prism based on experimental data available in the literature. The comparison of the derived results with the experimental findings demonstrates the ability of artificial neural networks to approximate the compressive strength of masonry walls in a reliable and robust manner.- (undefined
The Science Performance of JWST as Characterized in Commissioning
This paper characterizes the actual science performance of the James Webb Space Telescope (JWST), as determined from the six month commissioning period. We summarize the performance of the spacecraft, telescope, science instruments, and ground system, with an emphasis on differences from pre-launch expectations. Commissioning has made clear that JWST is fully capable of achieving the discoveries for which it was built. Moreover, almost across the board, the science performance of JWST is better than expected; in most cases, JWST will go deeper faster than expected. The telescope and instrument suite have demonstrated the sensitivity, stability, image quality, and spectral range that are necessary to transform our understanding of the cosmos through observations spanning from near-earth asteroids to the most distant galaxies
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